UNL researchers link healthy brain aging to nutritional profile

Scientists often study these patterns by tracking participants’ diets through questionnaires. Such studies have linked a Mediterranean diet focused on plant foods and healthy fats — vegetables, fruits, whole grains and extra-virgin olive oil — to improved physical health outcomes, including reduced cardiovascular risk.

Questions remain about whether diet and nutrition can also promote brain health. The only options so far to prevent accelerated brain aging are to protect against risk factors such as high blood pressure, alcohol and smoking.

Now, a new study led by a University of Nebraska-Lincoln researcher has identified a distinct nutritional biomarker profile in healthy older adults that is associated with healthy brain aging. And while the researchers didn’t specifically examine the Mediterranean diet, the nutrient profile they identified shares some nutrients with the popular diet.

“We found that there were certain nutritional biomarker patterns that were associated with healthy brain aging,” said Aron Barbey, director of UNL’s Center for Brain, Biology and Behavior. “And when we looked at those biomarker patterns, we found that there were nutrients that you also tend to find in the Mediterranean diet.”

The study, recently published in Nature Publishing Group Aging, involved 100 healthy adults ages 65 to 75. The other members of the research team were Jisheng Wu, a doctoral student at UNL, and Christopher Zwilling, a researcher at the University of Illinois at Urbana-Champaign.

In it, the researchers combined brain imaging measures of brain structure, function and metabolism with cognitive assessments that measured intelligence, executive function and memory. Those measures revealed two types of brain aging among the participants — accelerated and slower than expected — compared to the participants’ chronological age. The difference in brain age between the two groups was 5.4 years, a statistically significant margin.

Instead of using so-called food frequency questionnaires to characterize participants’ dietary patterns, the researchers assessed the nutritional status of participants who fell into the delayed brain aging group, using biomarkers in their blood.

Barbey noted that the questionnaires, which are traditionally used to characterize dietary patterns, can be very valuable in describing individual diets. But they have limitations because people typically can’t accurately remember which foods — or the amounts of foods — they eat each day. Different people also metabolize and absorb nutrients differently, and foods themselves can have different nutrient densities depending on how they’re grown, harvested and prepared.

That has prompted researchers in recent years to couple questionnaires with blood-based biomarkers, allowing them to quantify the nutritional value of a participant’s blood.

“That gives a more direct picture of an individual’s nutritional status,” Barbey said.

The study found that people in the group with delayed brain aging had higher concentrations of 13 key nutrients compared to the group with accelerated brain aging.

The nutritional profile included several food categories associated with healthy brain aging: seven fatty acids, three antioxidants and carotenoids, two forms of vitamin E, and choline.

Dietary sources of these nutrients include fish and shellfish, as well as many seeds, nuts and seed oils, and a variety of colorful fruits and vegetables. At least one type of fatty acid on the list comes from dairy products. Animal proteins such as meat, poultry, fish and eggs are important sources of choline, along with cruciferous vegetables such as broccoli and cauliflower and certain beans.

“This is promising evidence to further support the kind of recommendations that have been made,” Barbey said. “The Mediterranean diet is a broad dietary pattern that includes a number of these nutrients that we observed in our study.”

But Barbey stressed that the study is an observational study, which calls for randomized, controlled trials to determine whether feeding participants specific foods and increasing dietary biomarkers would have beneficial effects on their cognitive performance and brain health. That, in turn, could lead to nutritional interventions designed to promote brain health.

Meanwhile, there is a lot of scientific and medical interest in understanding how nutrition affects brain health, he said.

The National Institutes of Health recently launched a 10-year strategic plan to significantly accelerate nutrition research. And Barbey is co-editor of a forthcoming special collection for the Journal of Nutrition, “Nutrition and the Brain — Exploring Pathways to Optimal Brain Health Through Nutrition.” Papers will be published next year.

“What we’re all trying to do in the nutritional sciences is that evidence-based research can lead to effective public policy recommendations about diet and nutrition and how that can promote health,” Barbey said. “But unfortunately, more research is needed to get to that stage.”